Abstract
Multidrug resistance is a leading public health challenge that is causing a significant increase in mortality and morbidity. If antimicrobial resistance (AMR) remains unsolved, it may cause 10 million deaths every year. Along with a public health concern, it is also a financial concern that would cause 2-3.5% reduction in Gross Domestic Product (GDP) and a 100 trillion USD loss to the world. One of the ways to combat AMR is to discover new antibiotics. This study was aimed to evaluate the antibiofilm and antibacterial potencies of essential oil of Nigella sativa. Standard microbiological guidelines (CLSI) were used for the identification and antibiogram of selected strains of MRSA. Moreover, a time-kill assay of MRSA against Thymoquinone extracted from Nigella Sativa was also performed. Five strains, including four MRSA strains from implants related infections and one standard strain ATCC 25923, were examined. GC-MS identified components of essential oil of Nigella Sativa. Thymoquinone and p-cymene, major compounds of essential oil, were subjected to antibacterial and antibiofilm activities. Thymoquinone revealed strong inhibitory activities against MRSA strains. Zone inhibition measured 22 to 44 mm, and MIC values ranged from 26 to 43 Ul/mL. Thymoquinone also exhibited strong antibiofilm activity against biofilm producer MDR strains of Staphylococcus aureus.
Highlights
Difficult to treat infections include implant-related infections, and Staphylococcus aureus is the major contributor to these chronic infections
Standard inocula containing 5X106 CFU / mL of Methicillin-resistant and biofilm-forming Staphylococcus aureus (MRSA) was prepared, and 10μl of this inocula was added to the microtiter plate along with Thymoquinone, except for the sterility and negative control wells
Thymoquinone concentration that completely inhibited the bacteria growth was considered as Minimum inhibitory concentration (MIC)
Summary
Difficult to treat infections include implant-related infections, and Staphylococcus aureus is the major contributor to these chronic infections. Those having the potential to form a biofilm of medical devices. Resistance to antibacterial drugs diverted research into new antibiotics, especially plant-derived compounds. Essential oils of medicinal plants are proved to have excellent antibacterial activity and antioxidant function (Memarzadeh, Gholami et al 2020). Some plants and essential oils against Staphylococcus aureus are recently reported to remove biofilm effectively. Some studies have shown that combining essential oils and antibiotics to eliminate S. aureus is very successful (Memarzadeh, Gholami et al 2020). The current study is designed to investigate the antibacterial and antibiofilm potential of Thymoquinone against MRSA clinical strains isolated from catheter-related infections
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